Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$219.60	3.560%	$227.4178	$227.42	$227.40	$227.40
Purchase #2	$161.46	3.789%	$167.5777	$167.58	$167.60	$167.60
Purchase #3	$127.80	12.406%	$143.6549	$143.65	$143.65	$143.70
Purchase #4	$244.81	7.218%	$262.4804	$262.48	$262.50	$262.50
Purchase #5	$102.43	13.852%	$116.6186	$116.62	$116.60	$116.60
Purchase #6	$195.28	13.825%	$222.2775	$222.28	$222.30	$222.30
Purchase #7	$25.44	11.641%	$28.4015	$28.40	$28.40	$28.40
7 purchase totals =	$1,076.82		$1,168.4284	$1,168.43	$1,168.45	$1,168.50